Seat Reservation Issues Rome to Lauterbrunnen

Hi all,

I’m trying to book my seat reservations from Rome to Lauterbrunnen on the 14th of July, preferably on the 09:25 train from Rome. 

For the first leg of the journey, from Rome to Milan, it says ‘Prices unavailable - No price results were found. Pass holder reservations may be sold out for this connection, but there are other ways to check for available seats—more info below our timetable.’

Can anyone help? Is this simply an issue with the interrail website? Is it possible to book it with the Italian rail company directly.

Any help would be much appreciated!